@inproceedings{46398, abstract = {{With this paper we contribute to the understanding of the success of 2-opt based local search algorithms for solving the traveling salesman problem (TSP). Although 2-opt is widely used in practice, it is hard to understand its success from a theoretical perspective. We take a statistical approach and examine the features of TSP instances that make the problem either hard or easy to solve. As a measure of problem difficulty for 2-opt we use the approximation ratio that it achieves on a given instance. Our investigations point out important features that make TSP instances hard or easy to be approximated by 2-opt.}}, author = {{Mersmann, Olaf and Bischl, Bernd and Bossek, Jakob and Trautmann, Heike and Wagner, Markus and Neumann, Frank}}, booktitle = {{Learning and Intelligent Optimization}}, editor = {{Hamadi, Youssef and Schoenauer, Marc}}, isbn = {{978-3-642-34413-8}}, pages = {{115–129}}, publisher = {{Springer Berlin Heidelberg}}, title = {{{Local Search and the Traveling Salesman Problem: A Feature-Based Characterization of Problem Hardness}}}, doi = {{https://doi.org/10.1007/978-3-642-34413-8_9}}, year = {{2012}}, } @article{54937, abstract = {{Purpose: The epithelial sodium channel (ENaC) is typically expressed in sodium-absorbing epithelia. Several reports suggest that ENaC is also expressed in ocular tissues and may play a role in aqueous humor secretion and glaucoma. However, the precise localization of ENaC in the human eye is still unclear. Here, the authors studied ENaC expression in 12 normal human donor eyes and in six eyes of patients with glaucoma. Methods: Quantitative real-time PCR was used to investigate the expression of $\alpha$-, $\beta$-, $\gamma$-, and $\delta$-ENaC transcripts in ocular tissues. In addition, the authors performed immunohistochemical studies using recently generated antibodies against human $\beta$- and $\gamma$-ENaC. Results: At the mRNA level, all four ENaC subunits were found to be expressed in a wide range of ocular tissues from normal and glaucomatous human eyes, with the cornea, ciliary body, iris, and retina showing the highest expression levels. At the protein level, $\beta$- and $\gamma$-ENaC subunits showed distinct distribution patterns and could be immunolocalized primarily to the cell membranes of epithelial cells of the cornea and to the conjunctiva, iris, ciliary body, lens, and retinal pigment epithelium but also to vascular endothelial cells, smooth muscle cells, stromal cells, and retinal neurons. The authors found no altered mRNA level of any subunit in glaucomatous eyes. Conclusions: All four ENaC subunits ($\alpha$$\beta$$\gamma$$\delta$) are expressed in the normal human eye, with distinct localization of subunits possibly reflecting different functional states of the channel. The (patho-)physiological roles of ENaC in the various localizations in the eye remain to be determined.}}, author = {{Krueger, Bettina and Schlötzer-Schrehardt, Ursula and Haerteis, Silke and Zenkel, Matthias and Chankiewitz, Verena E. and Amann, Kerstin U. and Kruse, Friedrich E. and Korbmacher, Christoph}}, journal = {{Investigative Opthalmology & Visual Science}}, number = {{2}}, pages = {{596–604}}, publisher = {{Association for Research in Vision and Ophthalmology (ARVO)}}, title = {{{Four Subunits ($\alpha$$\beta$$\gamma$$\delta$) of the Epithelial Sodium Channel (ENaC) Are Expressed in the Human Eye in Various Locations}}}, doi = {{10.1167/iovs.11-8581}}, volume = {{53}}, year = {{2012}}, } @article{54930, abstract = {{Background: Increased expression of the pro-fibrotic protein connective tissue growth factor (CTGF) has been detected in injured kidneys and elevated urinary levels of CTGF are discussed as prognostic marker of chronic kidney disease. There is evidence that epithelial cells lining the renal tubular system contribute to uptake and secretion of CTGF. However, the role of different types of tubular epithelial cells in these processes so far has not been addressed in primary cultures of human cells. Results: Tubular epithelial cells of proximal and distal origin were isolated from human kidneys and cultured as polarized cells in insert wells. The pro-fibrotic stimuli lysophosphatidic acid (LPA) and transforming growth factor $\beta$ (TGF-$\beta$) were used to induce CTGF secretion.LPA activated CTGF secretion in proximal tubular cells when applied from either the apical or the basolateral side as shown by immunocytochemistry. CTGF was secreted exclusively to the apical side. Signaling pathways activated by LPA included MAP kinase and Rho kinase signaling. TGF-$\beta$ applied from either side also stimulated CTGF secretion primarily to the apical side with little basolateral release.Interestingly, TGF-$\beta$ activation induced different signaling pathways depending on the side of TGF-$\beta$ application. Smad signaling was almost exclusively activated from the basolateral side most prominently in cells of distal origin. Only part of these cells also synthesized CTGF indicating that Smad activation alone was not sufficient for CTGF induction. MAP kinases were involved in apical TGF-$\beta$-mediated activation of CTGF synthesis in proximal cells and a subset of epithelial cells of distal origin. This subpopulation of distal tubular cells was also able to internalize recombinant apical CTGF, in addition to proximal cells which were the main cells to take up exogenous CTGF. Conclusions: Analysis of polarized human primary renal epithelial cells in a transwell system shows that vectorial secretion of the pro-fibrotic protein CTGF depends on the cell type, the stimulus and the signaling pathway activated. In all conditions, CTGF was secreted mainly to the apical side upon TGF-$\beta$ and LPA treatment and therefore, likely contributes to increased urinary CTGF levels in vivo. Moreover, CTGF secreted basolaterally may be active as paracrine pro-fibrotic mediator.}}, author = {{Zuehlke, Jonathan and Ebenau, Astrid and Krueger, Bettina and Goppelt-Struebe, Margarete}}, journal = {{Cell Communication and Signaling}}, number = {{1}}, publisher = {{Springer}}, title = {{{Vectorial secretion of CTGF as a cell-type specific response to LPA and TGF-$\beta$ in human tubular epithelial cells}}}, doi = {{10.1186/1478-811x-10-25}}, volume = {{10}}, year = {{2012}}, } @article{54934, abstract = {{Aldosterone is thought to be the main hormone to stimulate the epithelial sodium channel (ENaC) in the aldosterone-sensitive distal nephron (ASDN) comprising the late distal convoluted tubule (DCT2), the connecting tubule (CNT) and the entire collecting duct (CD). There is immunohistochemical evidence for an axial gradient of ENaC expression along the ASDN with highest expression in the DCT2 and CNT. However, most of our knowledge about renal ENaC function stems from studies in the cortical collecting duct (CCD). Here we investigated ENaC function in the transition zone of DCT2/CNT or CNT/CCD microdissected from mice maintained on different sodium diets to vary plasma aldosterone levels. Single-channel recordings demonstrated amiloride-sensitive Na(+) channels in DCT2/CNT with biophysical properties typical for ENaC previously described in CNT/CCD. In animals maintained on a standard salt diet, the average ENaC-mediated whole cell current ($\Delta$I(ami)) was higher in DCT2/CNT than in CNT/CCD. A low salt diet increased $\Delta$I(ami) in CNT/CCD but had little effect on $\Delta$I(ami) in DCT2/CNT. To investigate whether aldosterone is necessary for ENaC activity in the DCT2/CNT, we used aldosterone synthase knockout (AS(-/-)) mice that lack aldosterone. In CNT/CCD of AS(-/-) mice, $\Delta$I(ami) was lower than that in wild-type (WT) animals and was not stimulated by a low salt diet. In contrast, in DCT2/CNT of AS(-/-) mice, $\Delta$I(ami) was similar to that in DCT2/CNT of WT animals both on a standard and on a low salt diet. We conclude that ENaC function in the DCT2/CNT is largely independent of aldosterone which is in contrast to its known aldosterone sensitivity in CNT/CCD.}}, author = {{Nesterov, Viatcheslav and Dahlmann, Anke and Krueger, Bettina and Bertog, Marko and Loffing, Johannes and Korbmacher, Christoph}}, journal = {{American Journal of Physiology-Renal Physiology}}, number = {{9}}, pages = {{F1289–F1299}}, publisher = {{American Physiological Society}}, title = {{{Aldosterone-dependent and -independent regulation of the epithelial sodium channel (ENaC) in mouse distal nephron}}}, doi = {{10.1152/ajprenal.00247.2012}}, volume = {{303}}, year = {{2012}}, } @article{54939, abstract = {{Background: Renal tubular epithelial cells of proximal and distal origin differ markedly in their physiological functions. Therefore, we hypothesized that they also differ in their capacity to undergo epithelial to mesenchymal alterations. Results: We used cultures of freshly isolated primary human tubular cells. To distinguish cells of different tubular origin we took advantage of the fact that human proximal epithelial cells uniquely express N-cadherin instead of E-cadherin as major cell-cell adhesion molecule. To provoke mesenchymal alteration we treated these cocultures with TGF-$\beta$ for up to 6 days. Within this time period, the morphology of distal tubular cells was barely altered. In contrast to tubular cell lines, E-cadherin was not down-regulated by TGF-$\beta$, even though TGF-$\beta$ signal transduction was initiated as demonstrated by nuclear localization of Smad2/3. Analysis of transcription factors and miRNAs possibly involved in E-cadherin regulation revealed high levels of miRNAs of the miR200-family, which may contribute to the stability of E-cadherin expression in human distal tubular epithelial cells. By contrast, proximal tubular epithelial cells altered their phenotype when treated with TGF-$\beta$. They became elongated and formed three-dimensional structures. Rho-kinases were identified as modulators of TGF-$\beta$-induced morphological alterations. Non-specific inhibition of Rho-kinases resulted in stabilization of the epithelial phenotype, while partial effects were observed upon downregulation of Rho-kinase isoforms ROCK1 and ROCK2. The distinct reactivity of proximal and distal cells was retained when the cells were cultured as polarized cells. Conclusions: Interference with Rho-kinase signaling provides a target to counteract TGF-$\beta$-mediated mesenchymal alterations of epithelial cells, particularly in proximal tubular epithelial cells. Furthermore, primary distal tubular cells differed from cell lines by their high phenotypic stability which included constant expression of E-cadherin. Our cell culture system of primary epithelial cells is thus suitable to understand and modulate cellular remodeling processes of distinct tubular cells relevant for human renal disease.}}, author = {{Keller, Christof and Kroening, Sven and Zuehlke, Jonathan and Kunath, Frank and Krueger, Bettina and Goppelt-Struebe, Margarete}}, issn = {{1932-6203}}, journal = {{PLOS ONE}}, number = {{8}}, pages = {{e43584}}, publisher = {{Public Library of Science}}, title = {{{Distinct Mesenchymal Alterations in N-Cadherin and E-Cadherin Positive Primary Renal Epithelial Cells}}}, doi = {{10.1371/journal.pone.0043584}}, volume = {{7}}, year = {{2012}}, } @article{39724, author = {{Redler, Andreas and Kitzerow, Heinz-Siegfried}}, issn = {{1042-7147}}, journal = {{Polymers for Advanced Technologies}}, keywords = {{Polymers and Plastics}}, number = {{1}}, pages = {{7--9}}, publisher = {{Wiley}}, title = {{{Three-dimensional structure in holographic polymer-dispersed liquid crystals}}}, doi = {{10.1002/pat.3040}}, volume = {{24}}, year = {{2012}}, } @article{40231, author = {{Meier-Gräwe, Uta and Wagenknecht, Inga}}, journal = {{Frühe Kindheit}}, pages = {{24--29}}, publisher = {{Deutsche Liga für das Kind in Familie und Gesellschaft e. V.}}, title = {{{Frühe Hilfen sind eine Zukunftsinvestition}}}, volume = {{14}}, year = {{2012}}, } @inproceedings{40820, abstract = {{An alternating optimization algorithm was recently proposed for the K-user multiple-input multiple-output (MIMO) interference channel. For flat-fading channels and feasible problems, this algorithm successfully aligns the interfering signals exploiting the spatial dimensions. In this paper, we consider the case in which all pairwise MIMO channels are frequency-selective (convolutive), and the users transmit broadband signals using a single-carrier scheme. Unlike the flat-fading case, for frequency-selective channels it is necessary to add a spectral mask in the frequency response of the precoders and decoders to avoid trivial solutions. We show in the paper that each step of the alternating minimization algorithm can be reformulated as a convex optimization problem in which the autocorrelation function of the precoders or decoders is obtained. Upon convergence, a final spectral factorization stage must be applied to obtain the precoders and decoders from their autocorrelation functions. Simulation results are provided to illustrate the performance of the proposed algorithm.}}, author = {{Lameiro, Christian and Vía, Javier and Santamaría, Ignacio and Heath Jr., Robert W.}}, booktitle = {{Proc.\ IEEE Int.\ Conf.\ Acoustics, Speech and Signal Process.}}, title = {{{Interference Leakage Minimization for Convolutive MIMO Interference Channels}}}, doi = {{10.1109/ICASSP.2012.6288506}}, year = {{2012}}, } @article{40810, abstract = {{This paper considers large multiple-input multiple-output (MIMO) communication systems with linear precoding and linear minimum mean-squared error (LMMSE) equalization based on the iterative conjugate gradient (CG) algorithm. Convergence of the CG algorithm is fast when the eigenvalues of the received signal’s covariance matrix are clustered, suggesting that mean-squared error and receiver complexity can be managed with judicious precoder design. In order to accelerate convergence of an iterative CG receiver, we incorporate constraints on two measures of eigenvalue clustering into the precoder design. Closed-form solutions to the optimal precoders are derived using majorization theory and convex optimization techniques. We show that if there are constraints on receiver complexity, the proposed precoders can improve performance for large MIMO systems operating over slowly time-varying fading channels.}}, author = {{Tong, Jun and Schreier, Peter J. and Weller, Steven R.}}, journal = {{IEEE Trans.\ Wireless Comm.}}, number = {{8}}, pages = {{2828–2837}}, title = {{{Linear precoding for MIMO systems with low-complexity receivers}}}, doi = {{10.1109/TWC.2012.070912.110877}}, volume = {{11}}, year = {{2012}}, } @article{39520, author = {{Brockmeier, A and Rodriguez, F J Santos and Harrison, M and Hilleringmann, Ulrich}}, issn = {{0960-1317}}, journal = {{Journal of Micromechanics and Microengineering}}, keywords = {{Electrical and Electronic Engineering, Mechanical Engineering, Mechanics of Materials, Electronic, Optical and Magnetic Materials}}, number = {{12}}, publisher = {{IOP Publishing}}, title = {{{Surface tension and its role for vertical wet etching of silicon}}}, doi = {{10.1088/0960-1317/22/12/125012}}, volume = {{22}}, year = {{2012}}, } @article{39522, author = {{Brockmeier, A and Rodriguez, F J Santos and Harrison, M and Hilleringmann, Ulrich}}, issn = {{0960-1317}}, journal = {{Journal of Micromechanics and Microengineering}}, keywords = {{Electrical and Electronic Engineering, Mechanical Engineering, Mechanics of Materials, Electronic, Optical and Magnetic Materials}}, number = {{12}}, publisher = {{IOP Publishing}}, title = {{{Surface tension and its role for vertical wet etching of silicon}}}, doi = {{10.1088/0960-1317/22/12/125012}}, volume = {{22}}, year = {{2012}}, } @inproceedings{3980, abstract = {{Paper Abstract High harmonic generation is investigated for a two-band model of a semiconductor nanostructure. Similar to an atomic two-level system, the semiconductor emits high harmonic radiation. We show how one can specifically enhance the emission for a given frequency by applying a non-trivially shaped laser pulse. Therefore, the semiconductor Bloch equations including the interband and additionally the intraband dynamics are solved numerically and the spectral shape of the input pulse is computed via an optimization algorithm. It is demonstrated that desired emission frequencies can be favored even though the overall input power is kept constant. We also suggest special metallic nano geometries to achieve enhanced localized optical fields. They are found by geometric optimization.}}, author = {{Reichelt, Matthias and Hildebrandt, Andre and Walther, Andrea and Förstner, Jens and Meier, Torsten}}, booktitle = {{Ultrafast Phenomena and Nanophotonics XVI}}, isbn = {{9780819489036 }}, keywords = {{tet_topic_shg}}, publisher = {{SPIE}}, title = {{{Engineering high harmonic generation in semiconductors via pulse shaping}}}, doi = {{10.1117/12.906338}}, volume = {{8260}}, year = {{2012}}, } @article{22953, abstract = {{The generation of specific high harmonics for an optical two-level system is elucidated. The desired emitted radiation can be induced by a carefully designed excitation pulse, which is found by a multiparameter optimization procedure. The presented mechanism can also be applied to semiconductor structures for which the calculations result in much higher emission frequencies. The optimization procedure is either performed using a genetic algorithm or a rigorous mathematical optimization technique.}}, author = {{Reichelt, Matthias and Walther, Andrea and Meier, Torsten}}, issn = {{0740-3224}}, journal = {{Journal of the Optical Society of America B}}, number = {{2}}, title = {{{Tailoring the high-harmonic emission in two-level systems and semiconductors by pulse shaping}}}, doi = {{10.1364/josab.29.000a36}}, volume = {{29}}, year = {{2012}}, } @article{52225, author = {{Schäfer, Mirko and Wagner, Johannes and Schlüter, Alexander and Hesselbach, Jens}}, issn = {{2305-9974}}, journal = {{SNE Simulation Notes Europe}}, number = {{1}}, pages = {{1--6}}, publisher = {{ARGESIM Arbeitsgemeinschaft Simulation News}}, title = {{{Energy Flows in Industrial Buildings and Machines using the Example of a Node Model}}}, doi = {{10.11128/sne.22.tn.10103}}, volume = {{22}}, year = {{2012}}, } @inproceedings{60458, abstract = {{Digital 3D models are key components in many industrial and scientific sectors. In numerous domains polygonmeshes have become a de facto standard for model representation. In practice meshes often have a number ofdefects and flaws that make them incompatible with quality requirements of specific applications. Hence, repairingsuch defects in order to achieve compatibility is a highly important task - in academic as well as industrial applications. In this tutorial we first systematically analyze typical application contexts together with their requirementsand issues, as well as the various types of defects that typically play a role. Subsequently, we considerexisting techniques to process, repair, and improve the structure, geometry, and topology of imperfect meshes,aiming at making them appropriate to case-by-case requirements. We present seminal works and key algorithms,discuss extensions and improvements, and analyze the respective advantages and disadvantages depending onthe application context. Furthermore, we outline directions where further research is particularly important orpromising.}}, author = {{Campen, Marcel and Attene, Marco and Kobbelt, Leif}}, booktitle = {{Eurographics 2012 Tutorials}}, title = {{{A Practical Guide to Polygon Mesh Repairing}}}, doi = {{10.2312/CONF/EG2012/TUTORIALS/T4}}, year = {{2012}}, } @inproceedings{3965, abstract = {{We design the geometrical shape of plasmonic nanostructures to achieve field patterns with desired properties. For this, we combine Maxwell simulations and automatic optimization techniques. By allowing variations of the geometrical shape, which can be based on either boxes or arbitrary polygons, we maximize the desired objective.}}, author = {{Hildebrandt, Andre and Reichelt, Matthias and Meier, Torsten and Förstner, Jens}}, keywords = {{tet_topic_optical antenna, tet_topic_plasmonics}}, location = {{Bad Honnef}}, number = {{59}}, publisher = {{AIP AIP Conference Proceedings 1475}}, title = {{{Optimization of the intensity enhancement in plasmonic nanoantennas}}}, doi = {{10.1063/1.4750095}}, year = {{2012}}, } @article{52868, author = {{Grimme, Britta and Lipinski, John and Schöner, Gregor}}, journal = {{Experimental brain research}}, pages = {{185–200}}, publisher = {{Springer}}, title = {{{Naturalistic arm movements during obstacle avoidance in 3D and the identification of movement primitives}}}, volume = {{222}}, year = {{2012}}, } @inproceedings{25421, author = {{Ngonga Ngomo, Axel-Cyrille and Auer, Sören}}, booktitle = {{{IJCAI} 2011, Proceedings of the 22nd International Joint Conference on Artificial Intelligence, Barcelona, Catalonia, Spain, July 16-22, 2011}}, editor = {{Walsh, Toby}}, pages = {{2312--2317}}, publisher = {{{IJCAI/AAAI}}}, title = {{{LIMES - A Time-Efficient Approach for Large-Scale Link Discovery on the Web of Data}}}, doi = {{10.5591/978-1-57735-516-8/IJCAI11-385}}, year = {{2011}}, } @inproceedings{25427, author = {{Shekarpour, Saeedeh and Auer, Sören and Ngonga Ngomo, Axel-Cyrille and Gerber, Daniel and Hellmann, Sebastian and Stadler, Claus}}, booktitle = {{Proceedings of the 2011 {IEEE/WIC/ACM} International Conference on Web Intelligence, {WI} 2011, Campus Scientifique de la Doua, Lyon, France, August 22-27, 2011}}, editor = {{Boissier, Olivier and Benatallah, Boualem and P. Papazoglou, Mike and W. Ras, Zbigniew and Hacid, Mohand-Said}}, pages = {{203--210}}, publisher = {{{IEEE} Computer Society}}, title = {{{Keyword-Driven SPARQL Query Generation Leveraging Background Knowledge}}}, doi = {{10.1109/WI-IAT.2011.70}}, year = {{2011}}, } @inproceedings{26660, abstract = {{During rescue scenarios it is indispensable to obtain an overview of the situation. Unmanned aerial vehicles (UAVs) can gather the necessary information in a fast and efficient way. This paper presents an approach for path planning in 3D environments offering a solution to explore disaster areas including, e.g., partially or completely destroyed buildings. Using multiple UAVs decreases the time needed to receive a complete overview if the problem of coordination and task allocation is solved. We present an approach for the use of multiple UAVs. The UAVs work in a distributed manner without any central coordination instance and cover the exploration of terrains as well as goal-oriented path planning. When using multiple UAVs redundant exploration is avoided through the use of inter-UAV-communication. The approach is based on potential fields and uses the simplicity of the gradient method to calculate paths for fast exploration of the terrain. }}, author = {{Rasche, Christoph and Stern, Claudius and Kleinjohann, Lisa and Kleinjohann, Bernd}}, booktitle = {{The 5th International Conference on Automation, Robotics and Applications (ICARA 2011)}}, title = {{{A Distributed Multi-UAV Path Planning Approach for 3D Environments}}}, year = {{2011}}, }